make-up water in garage hydronic system where there is no water supply

tbignell

Only water in this detached garage/shop will be via “hose” from main house.
What do you recommend for make up water after initial startup?
Should I plan for a small storage tank somehow connected to system?

STEVEusaPA

I recommend a low water cut-off.
Is it a glycol mix?
You shouldn't lose enough water to worry about it. Make sure it's good at the start of the season, check it every time you walk by it.

HomerJSmith

https://www.supplyhouse.com/Axiom-MF200-MF200-PRESSURE-PAL-Hydronic-Mini-System-Feeder-6-Gallon

mattmia2

You can fill it and leave it, the expansion tank can hold enough to last at least a season if not much longer as long as you make sure you don't have any leaks.

If you want to have an automatic feed system, get a large (maybe 5 or 10 gal) expansion tank, connect it to the system with a PRV and fill the tank with extra water or glycol and pressurize it to a fair bit above the system pressure.

STEVEusaPA

A regular expansion tank alone is part of the system. It doesn't add or take away water from the system.
I also wouldn't spend $500+ bucks for the feeder @HomerJSmith mentioned.
If you have no leaks, you will need very little to almost no water added, once a year. I have a 6 zone hydronic system in my house, feed closed, LWCO. I've only put about a gallon in over the last 10 years.

GroundUp

The Axiom feeders are nice, but unless you have a leak somewhere completely unnecessary. Check it once in awhile when you walk by just to be sure, but without a leak the pressure will never drop in a closed system. Should you need some on occasion, stringing out a hose will be a lot more cost effective than buying a feeder

HomerJSmith

Mattmia2, Yes, I have done that. I use something similar to that on commissioning to supply anti-freeze makeup water.

I learned that from "HotRod". It has a Caleffi feed valve and a Webstone expansion tank valve in series with a hose bibb connected to an expansion tank pressurized to 20 psi air charge and a 60 psi water supply. Cheaper than an Axion.

Thank you, "HotRod" for the great idea. I'll take picture of mine, tomorrow and submit it.

mattmia2

there was a post here a few weeks ago where someone had a glycol system with that installed as a feeder. the rest of the system was abysmal, but i liked that idea to feed the glycol

tbignell

Thanks all for your responses!

hot_rod

Mild- wild for building a fill tank, any size tank will work, even small well tanks. Add a gauge, hose connection for portable use.

Note the Caleffi AutoFill have checks built in for back flow protection.

tbignell

Thanks for all your comments... we're now through the worst of the heating season and success!
This super simple system kept my garage and shop between 50 and 60 degrees all winter through high winds and -20C temps.
Details:
50' x 32' garage/shop with (3) garage doors, (2) human doors & (11) 36"x36" windows.
2000' of 1/2" PEX in 9 loops: 3x200' for 2-car garage, 2x200' for entrance and long hallway 4x250' for shop area.
Manifold serving all 9 loops, WiseWater pump (on medium flow - 78W), AO Smith HW Tank
I have pump set to run for 8 minutes every 2 hours delivering close to 130F water to all loops.
Flow rate is difficult to assess system is pressurized at around 12 PSI.
When pump is on I see around 15 PSI at manifold and the flow control valves each show around 1.0 liters per minute.
HW tank recovers in about 35 minutes and waits for the next interval.
I have noticed that after the pump shuts at 8 minutes the return manifold continues to rise in temperature to 70+F through convection as the warm water rises through the PEX.
I was nervous about make-up water initially but as many of you suggested... it appears for now that I have no leaks and no need.
Your comments are welcome (good or bad)...
Cheers and thanks again.
Ted

GroundUp

Why is the circ pump not simply tied to a thermostat so you can maintain a steady temp instead of the timer debacle?

tbignell

It's a fair question and I may transition back to a thermostat in the next heating season.
When I started the floor was already COLD and the HW tank cannot instantaneously provide BTU's like a boiler. So in my simplistic mind, to get more BTU's transferred into the floor, I needed a decent temperature differential and letting the HW heater recover between blasts of hot water to the floor seemed good. Initially I was sending every hour for 10-12 minutes... then through observation fell back to 2-hour intervals of 8 minutes which is just where return manifold starts to notice a rise.
There is no doubt that a thermostat would be nice... and will likely work fine if I start with a warm floor.
Good question - thanks.

mattmia2

there is no difference between circulating warmer water by waiting vs just letting the element heat the colder water continuously. you are adding the same amount of energy to the system either way(actually less with the cycling because the element in the water heater probably gets satisfied and turns off sometimes).

GroundUp

That's great, in theory, but in reality it doesn't work that way. The WH may be capable of producing 40,000 BTU per hour. Running the pump for the entire hour would yield 40,000 BTU in that case. Running it for 10 minutes per hour would only provide maybe 10,000 BTU. What you've done here is effectively reduce the input, the opposite of what you were hoping to accomplish

HomerJSmith

Late--The white tank is the feed tank to the sys. The air charge is 30 psi and the fluid is pumped up to 70 psi. The feed is into a Caleffi pressure reducing valve with gauge and is set to 15 psi to the sys expansion tank. I use a high head 1 hp pump to put 70 psi fluid into the tank.

The size of the white tank determines the amount of fluid that can be stored. The white tank is a potable water tank because the stored fluid has oxygen in it.

mattmia2

Isn't that basically what i said and got a disagree?

HomerJSmith

I gave you an agree!

GroundUp

@mattmia2 that was me, and I was disagreeing with the first part of your comment where you suggested that the system's regular expansion tank would hold enough for a season. It's not there for storage or "pressure buffer"

hot_rod

The Germans call it a safety seal, common in solar thermal glycol systems that do not have a fill system. Basically you oversize the expansion tank, under-pressurize it a few psi below your intended fill pressure. This allows the expansion tank itself to hold a gallon or so to replace displaced air as the system heats the first time.

The Caleffi solar package systems held about 6-8 gallons of glycol, we included a #30 expansion tank to provide plenty of expansion for the huge delta that a solar thermal undergoes, which would be outdoor ambient possibly below 0 to over 300°F under stagnation conditions. I think @EdTheHeaterMan explained nicely the expansion tank pre-charge a few psi low in a previous post.

If for some reason you expect a lot of air to vent out, a PIG system is an inexpensive option shown by @HomerJSmith

Another tip is run a new system up to 180F or more, for maybe an hour, that will drive most all the air out of solution, then lower it down to the intended operating temperature.

EdTheHeaterMan

hot_rod said:

I think @EdTheHeaterMan explained nicely the expansion tank pre-charge a few psi low in a previous post.

@hot_rod That is because when Dan H told me to "Think Like Water" in one of his seminars a hundred years ago (seems that long) I took him seriously. I have been all were ever since